Technical Field
The instant disclosure relates to a solar cell.
Related Art
Recently, various advanced technologies are developed to increase the conversion efficiency of solar cells so as to satisfy the market requirements of solar cells with high conversion efficiencies.
So far, solar cells with high conversion efficiencies include heterojunction with intrinsic thin-layer (HIT) solar cell, selective emitter solar cell, passivated emitter rear cell (PERC) solar cell, etc. Specifically, for the PERC solar cell, passivated techniques are applied to the solar cell to passivate the rear of the solar cell and emitter electrodes at the front of the solar cell, such that the recombination possibility of the electron-hole pair at the surface of the semiconductor substrate can be reduced, thereby improving the conversion efficiency of the solar cell.
Therefore, in manufacturing the rear of a PERC cell, firstly plasma-enhanced chemical vapor deposition (PECVD) techniques would be applied to the rear of a semiconductor substrate to form passivation layer, and then a plurality of openings is formed on the passivation layer through laser ablation or etching techniques. Next, aluminum pastes are screen printed on the passivation layer, and the aluminum pastes are passing through the openings and in contact with the semiconductor substrate. Lastly, silver pastes are screen printed on the semiconductor substrate. Therefore, the pastes are collectively sintered to form back electrodes and bus bars.
However, because there are openings formed by laser ablation under the bus bars of the existing PERC solar cell, the bus bars would be deformed or uneven easily when the pressure applied over the semiconductor substrate is not uniform. In addition, if too many openings in the passivation layer, the performance of the solar cell would be adversely affected. Although the Aluminum paste can recover part of the mechanical strength loss of the opening region, silver paste cannot, so the mechanical strength of the solar cell would draw down and raise the breakage rate.